Helsinki University of Technology

This thesis describes the development and characterisation of a novel biomembrane model suitable for electrochemical investigation, and its applicability in studies of biologically related phenomena. The model system consists of a lipid monolayer, deposited at a polarisable liquid – liquid interface with the Langmuir – Blodgett technique. Combinations of ac and dc electrochemical techniques with theoretical models are employed to obtain information on the phase transfer and membrane interactions of charged therapeutics at the monolayer-covered interface. The thesis comprises six publications and a thorough introduction to biological and model membranes. The first part of the thesis surveys background literature with relevance to the present work. Basic properties of biological membranes are discussed and existing biomembrane models reviewed. The presented literature serves as a reference point for the development and evaluation of the model system described in this thesis, and is frequently referred to in the discussion of the results. In the second part of the thesis, the essential results of the publications are summarised. Instead of an article-by-article approach, results from various publications are jointly presented under appropriate headings. The development, characterisation and applicability of the model system are discussed. In the last-mentioned section, emphasis lies on methods applicable to drug development and delivery. To this end, the usefulness of the model system in the construction of pH – potential diagrams, determination of drug membrane activity, and studies of drug transfer through polyelectrolyte multilayers, is investigated. Finally, in view of the obtained results, the future prospects of the system are assessed.